Best way to level gems to 150?
I've played D3 on and off for years, but am definitely not a very advanced player.
I have ~2200 paragon in non-seasonal and ~1300 this season. My highest solo GRs are 140 (a few seasons ago) and 120 (non-seasonal) with the same GoD Demon Hunter. My current seasonal WW Barbarian can do a 125 pretty comfortably and I'll probably be able to squeeze out a 130, but likely not much higher.
After all these years, I'd just love to have some 150 gems/augments, especially on my favourite characters (currently, my highest gems are 140 and my highest augments are 125). Generally, I'd love to be able to run 150 GRs solo, especially in non-seasonal and with no fishing.
Is there any build at all that I could expect to somewhat comfortably farm GR 150s with, while having ~3000 non-seasonal paragon? Or seasonal, if I don't expect to ever get above ~1500 paragon in a season?
Based on the leaderboards, I see that more people have done a GR150 solo with a Necromancer than with pretty much all the other characters combined. Is that the way to go?
Or is this all just too big of an ask and I should build a zbarb and join groups of better players?